Happy will they be who lend ear to the words of the dead.

To me it seems that those sciences are vain and full of error which are not born of experience, mother of all certainty, first-hand experience which in its origins, or means, or end has passed through one of the five senses.

Just as courage imperils life, fear protects it.

The eye which turns from a white object in the light of the sun and goes into a less fully lighted place will see everything as dark.

I have solved what color is, however ; I still have no idea about what line is.

The eye is the window of the human body through which it feels its way and enjoys the beauty of the world.

A clever man without wisdom is like a beautiful flower without fragrance.